Semi-conductive electrode system



Dec. 115, 1959 H. K. BECHERER 2,917,684

SEMI-CONDUCTIVE ELECTRODE SYSTEM Filed Sept. 5, 1956 \NVENTOR HANS KARL BECHER ER AGET United States Patent SEMI-CONDUCTIVE ELECTRODE SYSTEM Hans Karl Becherer, Hamburg, Germany, assignor, by

mesne assignments, to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Application September 5, 1956, Serial No. 608,067

Claims priority, application Netherlands September 29, 1955 3 Claims. (Cl. 317-234) This invention relates to semi-conductive electrode systems or devices comprising a semi-conductive body, one or more electrodes, and current-supply wires or leads connected to the electrodes.

It is known for such an electrode system, the semiconductive body of which may consist, for example, of germanium or silicon, to be subjected to an etching treatment after the electrodes and the current-supply wires have been provided. Since the conventional etching agents chemically attack not only the surface of the semi-conductive body, but also the supply wires, the risk is involved that the elements thus dissolving may contaminate the semi-conductive surface and this results in a material decline in the electrical properties of such a system.

The invention is based on the discovery that, although chromium and nickel, separately, are chemically attacked by the conventional etching agents, there are a plurality of alloys of such metals which are not attacked thereby.

According to the invention, at least one current-supply wire consists of a chromium-nickel alloy containing at least so large a percentage of each of said elements that chemical attack in the conventional etching agents does not occur. The alloy preferably contains at least 5% of each of said metals. An alloy which may satisfactorily be used contains 20% of chromium and 80% of nickel. (The percentages mentioned are percentages by weight.)

In order that the invention may be readily carried into effect, one embodiment will now be described, by way of example, with reference to the accompanying drawing.

The sole figure in the drawing is a diagrammatic sectional view of a crystal diode.

The diode comprises a germanium monocrystal 1 of area of 3 x 3 mms.

2,917,684 Patented Dec. 15, 1959 the n-type having a thickness of 0.5 mm. and a surface The specific resistance is, for example, 15 ohm-cm. With the aid of a small amount of tin 2 containing 10% of antimony, the crystal is soldered to a small plate of gold-coated molybdenum 3 having a coefficient of expansion approximately equal to that of germanium. A so-called alloy electrode 4, consisting of indium, is fused to the upper side of the crystal. A conductive lead or supply wire 5 secured in the electrode 4 consists of an alloy of 20% of chromium and of nickel.

Compositions of a few conventional baths for etching semi-conductive electrode systems are:

A B 1 d H 0 3 dl. HNO 1 dl. HP 3 dl. HF 1 dl. H 0 3 dl. CH COOH 0.1 dl. Br

As a rule, current-supply wires need, of course, to be manufactured from such an alloy only so far as they come into contact with the etching liquid.

What is claimed is:

1. In a semi-conductive device containing a semi-conductive body and a fused electrode thereon and subject to an etching treatment after the electrode has been made and contacted, a conductive lead connected to the electrode and of which the portion thereof adjacent the body is constituted of a chromium-nickel alloy containing sufficient chromium and nickel to resist chemical attack during the etching treatment.

2. In a semi-conductive device containing a semi-conductive body and a fused electrode thereon and subject to an etching treatment after the electrode has been made and contacted, a conductive lead connected to and contacting the electrode and consisting of a chromium-nickel alloy containing at least 5% of chromium and at least 5% of nickel.

3. A device as set forth in claim 2 wherein the alloy consists of about 20% of chromium and about 80% of nickel.

References Cited in the file of this patent UNITED STATES PATENTS 2,541,832 Quinn Feb. 13, 1951 2,542,727 Theuerer Feb. 20, 1951 2,677,079 McCreary Apr. 27, 1954 

1. IN A SEMI-CONDUCTIVE DEVICE CONTAINING A SEMI-CONDUCTIVE BODY AND A FUSED ELECTRODE THEREON AND SUBJECT TO AN ETCHING TREATMENT AFTER THE ELECTRODE HAS BEEN MADE AND CONTACTED, A CONDUCTIVE LEAD CONNECTED TO THE ELECTRODE AND OF WHICH THE PORTION THEREOF ADJACENT THE BODY IS CONSTITUTED OF A CHROMIUM-NICKEL ALLOY CONTAINING SUFFICIENT CHROMIUM AND NICKEL TO RESIST CHEMICAL ATTACK DURING THE ETCHING TREATMENT. 